//给字符串追加感叹号
fun String.addExt03(amount:Int = 1) = this + "!".repeat(amount)

fun <T> T.easyPrint03():T {
    println(this)
    return this
}

fun main() {
    "abc".easyPrint03().addExt03(2).easyPrint03()
    "ADB".let {  }
}